More than half of all investigated isolates (n ¼ 23; 65.7%) were
resistant to at least one class of antibiotic, and 16 (45.7%) of the
strains were classified as multi-drug resistant (MDR; resistant to
three or more classes of antibiotics). Overall, MDR enterococci were
common among isolates from RTE shrimps and were not common
among isolates obtained from raw or cooked shrimps. A high percentage
of isolates were resistant to TE (n ¼ 17; 48,6%), followed by
TGC and FOT (n ¼ 16; 45.7%), TEC (n ¼ 13; 37.1%), E (n ¼ 10; 28.6%),
NOR (n ¼ 6; 17.1%). Resistance to these antibiotics was higher in E.
faecalis than in other species. Taking into account the source of
isolation, strains isolated from RTE shrimps showed resistance to
antibiotics more often than strains isolated from other sources.
Resistance to LZD, and VAN antimicrobials, very important in human
medicine, was not found in any enterococci. Resistance to CIP,
also a clinically important drug, was found in 14.3% (n ¼ 5) of
strains, including three E. faecalis and one E. faecium isolated from
RTE shrimps and one E. faecalis isolated from raw shrimps. Resistance
to other antibiotics tested ranged from 8.6% to 2.9%. Since E.
faecalis is intrinsically resistant to QD, resistance data for this
antimicrobial was not reported. Resistance to QD was found only in
one E. casseliflavus strains. Twelve enterococci strains (34.3%) were
susceptible to all tested antimicrobials (Table 2).